One of today's major objectives to be met by technological means is to ensure the economical handling of available energy resources in generating and consuming power.
Power plants which are sizeable in terms of their installed generating capacity and which supply a large number of consumers and extensive geographical areas with electrical energy and district heat on a centralized basis are frequently employed to generate electrical energy and also to decouple district heat.
The centralized provisioning in this manner of electrical and thermal energy is cost-effective compared to decentralized provisioning employing a large number of smaller isolated plants and is particularly economical in operation.
Said known, what is termed combined heat and power generation is practically independent of the type of power station employed, the size of the power station, and the fuel used. The only crucial factor is for a heat source having a suitable primary-side temperature to be available for heating a heating medium. Hot water is today used almost exclusively as the heating medium.
To implement combined heat and power generation of the known type, heat that would otherwise have to be entirely or at least substantially dispersed unused into the surrounding area is usually decoupled from the power-plant process.
The heat source used for combined heat and power generation of this type can be, for example, steam from a steam turbine, which steam is taken, for instance, from a low-pressure section of the steam turbine. The heating medium can then be heated by the extracted steam through the latter's passing the condensation heat it contains to the heating medium by means of heat exchange.
This type of heat provisioning by means of combined heat and power generation of the kind described is especially economical because otherwise unused process heat is rendered usable, for example for heating buildings.
Contrary to the cited central provisioning with electrical and thermal energy, to generate refrigeration it is today known how to generate said refrigeration almost exclusively on a decentralized basis, mostly in block-type thermal power stations, or directly on site, mostly on the domestic premises themselves.
Said type of decentralized provisioning with refrigeration is very demanding in terms of cost and energy because either block-type thermal power stations have to be specially set up for the purpose of supplying consumers who have substantial refrigeration requirements or, in the case of refrigeration provisioning carried out directly on domestic premises, a large amount of electrical energy has to be expended in order to generate the required amount of refrigeration.